The overall goal of this project is to enhance the nation's ability to vaccinate adolescents in primary care practices. Most adolescents >11 years are now eligible to receive newly licensed adolescent vaccinations including human papilloma virus (HPV), meningococcal vaccine and tetanus-pertussis vaccine (TdaP). This new era of adolescent vaccinations will require additional visits to primary care practices for many adolescents. Systems are needed to track, remind, and recall adolescents for needed immunizations, particularly among low-income adolescents who have lower vaccination rates and fewer preventive healthcare visits. A potentially efficient strategy for reminder/recall for adolescents is to base these systems in managed care, since most adolescents are enrolled in health insurance organizations. Therefore, the aims of this study are to: 1. Design an adolescent immunization reminder/recall system with mailed or telephone messages, and based in managed care settings for low-income populations in the Rochester New York, region. 2. Evaluate the effectiveness of this managed care-based adolescent immunization reminder/recall system using a randomized clinical trial (RCT) to test mailed versus telephone (autodialer-based) reminder/recall versus control. Implement the RCT across diverse practices (pediatric/family physician, and different practice types) and adolescent populations (11-18yrs, and urban/suburban/rural regions). 3. Evaluate and compare the costs, cost-effectiveness and feasibility of the mailed / telephone systems. 4. Disseminate findings in collaboration with public health and professional organizations. For Aim 1, we will pilot test the reminder/recall systems and messages using qualitative methods, with input from parents, adolescents, and managed care experts. For Aim 2 we will evaluate, over 12 months, the effectiveness of mailed reminders vs telephone reminders vs standard of care control in improving (a) adolescent vaccination rates and (b) preventive visits and other preventive services. We will randomize 5,000 adolescents across 40 primary care practices in upstate NY. We will test the impact of reminder/recall using bivariate and multivariate analyses, for the entire population, and for subgroups of (a) adolescents (by age, gender, urban/suburban/rural residence);(b) practices (pediatric or family MD, and private office/clinic/health center);and (c) insurance (Medicaid or the State Children's Health Insurance Program). For Aim 3 we will measure and compare costs of the two reminder systems, and their cost-effectiveness, and will assess feasibility and generalizability to different settings. For Aim 4 we will work with experts to disseminate findings. By rigorously evaluating the effectiveness of immunization reminder/recall for adolescents across a wide spectrum of patients and practices, this study will provide critical information for practitioners and immunization and public health leaders to implement strategies to enhance adolescent immunizations and preventive care. Public Health Statement: Immunizations are one of the greatest public health achievements. The new era of adolescent immunizations will require new strategies to protect millions of adolescents from vaccine-preventable diseases including human papilloma virus (HPV), meningococcal vaccine, and tetanus-pertussis vaccine (TdaP). This study evaluates the effectiveness of patient reminder/recall in improving both adolescent immunization delivery and the delivery of other critical adolescent preventive services.